The subject matter disclosed herein relates generally to controlling an expansion valve, and more particularly to controlling an expansion valve using an anticipatory process to accommodate fast load changes in a refrigeration system.
Expansion valves, such as electronic expansion valves (EXVs) are used for metering refrigerant flow to an evaporator. The valves are typically slow moving and unable to keep up with fast loading (at startup or during rapid load change). Existing control methods may pre-open the expansion valve by a fixed number steps (or few discrete # of steps—e.g 50% and 100%). However, this may cause a low suction pressure fault (if the # of steps are too small compared to loading rate) or may cause compressor flooding (if the # of steps are too large compared to loading rate). Existing control methods do not employ provisions for pre-closing the valve, in case of load reduction, which exposes the chiller to potential compressor flooding.